Microwave plasma processing device and plasma processing gas supply member

ABSTRACT

A microwave plasma processing device and a gas supply member capable of forming a uniform thin film on a substrate to be processed. The microwave plasma processing device comprises fixing means of fixing a substrate to be processed onto the center axis in a plasma processing chamber, exhaust means of depressurizing the inside and outside of the substrate, a metal processing gas supply member present in the substrate and forming a reentrant cylindrical resonating system along with the plasma processing chamber, and microwave introducing means of introducing a microwave into the plasma processing chamber to process it, wherein a microwave sealing member is provided in a specified position of the substrate-holding portion of the fixing means, and the connection position of the microwave introducing means is set to a specified weak-field position out of a field intensity distribution formed in the interior of the plasma processing chamber.

TECHNICAL FIELD

The present invention relates to a microwave plasma processing device,and more particularly to a microwave plasma processing device which canstably and efficiently generate plasma when forming a chemical vapordeposition film to a plastic container.

BACKGROUND ART

A chemical vapor deposition method (CVD) is a technique which separatesout a reaction product in the form of a film on a surface of aprocessing target by vapor phase epitaxy in a high-temperatureatmosphere using a processing gas which causes no reaction at anordinary temperature, and is widely adopted in manufacture of asemiconductor, surface property modification of a metal or ceramic, andothers. In recent years, in the CVD, especially low-pressure plasma CVDhas been applied to surface property modification of a plasticcontainer, and an improvement in gas barrier properties in particular.

The plasma CVD performs thin-film growth by utilizing plasma, and it isbasically a method which causes in a vapor phase or on a processingtarget a chemical reaction of a substance generated from dissociationand coupling by discharging a gas containing a processing gas by usingan electrical energy of a high electric field under a reduced pressure,thereby depositing the substance on the processing target.

A plasma state is realized by glow discharge, corona discharge and arcdischarge and, as types of glow discharge in these discharge schemes,there are known a method utilizing direct-current glow discharge, amethod utilizing high-frequency glow discharge, a method utilizingmicrowave discharge and others.

As an example of forming a vapor disposition carbon film on plastic byutilizing high-frequency glow discharge, there has been disclosed acarbon film coated plastic container having a hard carbon film formed onan inner wall surface of the plastic container.

In the plasma CVD utilizing high-frequency glow discharge, however,since a so-called capacitive coupling type CVD device in which aninternal electrode is arranged in a container and an external electrodeis arranged outside the container must be used, there is a problem thata configuration of the device becomes complicated and the operation isalso complicated.

On the contrary, in microwave plasma CVD, since microwave discharge in achamber is utilized, the arrangement of an external electrode or aninternal electrode is unnecessary, and a configuration of a device canbe very simplified. Further, in regard to a level of depressurization inthe device, since producing microwave discharge in a plastic containeronly can suffice, the inside of the entire device does not have to bemaintained in a high vacuum state, and this method is superior in thesimplicity of the operation and the productivity.

Microwave discharge plasma is plasma which is superior in the efficiencyof generation of high-energy electrons, and is useful for the plasma CVDas high-density and high-reactivity plasma.

As a microwave plasma processing method and device aiming at a plasticcontainer, there has been disclosed a method by which a bottle iscoaxially arranged in a cylindrical microwave trapping chamber tosimultaneously ventilate the inside and outside of the bottle, aprocessing gas is caused to flow into the bottle for a predeterminedprocessing time, microwaves are introduced into the microwave trappingchamber and plasma is ignited and maintained in the bottle, therebyprocessing the bottle.

When the microwave plasma processing is utilized, however, since thereis a time lag between introduction of microwaves and generation ofplasma and this time lag is not fixed and greatly fluctuates inaccordance with each processing, there is a drawback that controllingprocessing conditions is difficult and the effect of processing isunstable.

Furthermore, since the state of plasma is unstable, there is a problemthat a container to be processed is locally subjected to thermaldeformation or a uniform thin film cannot be formed.

Here, although a method using an electrical spark, a method based onultraviolet ray irradiation, a method based on a magnetic fieldoperation and others are known as the plasma ignition method, any methodhas a problem that a configuration of a device becomes complicated.

Moreover, although ignition of plasma can be hastened by increasing anoutput of a microwave which is introduced into a plasma processingchamber, since processing using plasma with a high energy is carried outfrom a vapor deposition initial stage when the output of the microwaveis increased, an intermediate layer formed between a target substrate tobe processed and a vapor deposition film does not sufficiently grow,thereby reducing the adhesion between the target substrate to beprocessed and the vapor deposition film.

In order to solve the above-described problems, it is an object of thepresent invention to provide a microwave plasma processing device and aplasma processing gas supply member which can form a uniform thin filmon a target substrate to be processed by uniformly forming a processinggas into plasma with excellent energy efficiency, reduce a time fromintroduction of a microwave into a plasma processing chamber to plasmaemission, and control a timing of ignition of plasma.

DISCLOSURE OF THE INVENTION

In order to solve this problem, as a result of dedication to studies,the present inventors have discovered that a uniform thin film can beformed on a processing target with good energy efficiency by providing amicrowave sealing member to a predetermined position of asubstrate-holding portion of fixing means, specifying a length of aprocessing gas supply member with this position being used as areference, and specifying a connection position of microwave introducingmeans, and they have brought the present invention to completion.

Additionally, the present inventors have revealed that a microwaveoutput required to start plasma emission can be reduced by providing themicrowave sealing member to a predetermined position of asubstrate-holding portion of substrate fixing means which holds thesubstrate with a gap therebetween and a time from introduction of amicrowave into the plasma processing chamber to plasma emission can bereduced, and they have brought the present invention to completion.

Further, the present inventors have discovered that a uniform thin filmcan be formed on a processing target by using a porous pipe having anaperture distribution in a lengthwise direction as a gas supply memberwhich supplies a processing gas into the plasma processing chamber of aplasma processing device or by constituting the gas supply member to besectionalized into a metal electric field distribution stabilizing areaand a non-metal end gas induction area, and they have brought thepresent invention to completion.

That is, there is provided a microwave plasma processing deviceaccording to the present invention having: fixing means for fixing asubstrate as a processing target on a central axis in a plasmaprocessing chamber; exhausting means for depressurizing the inside andoutside of the substrate; a metal processing gas supply member which ispresent in the substrate and forms a reentrant cylindrical resonatingsystem along with the plasma processing chamber; and microwaveintroducing means for introducing a microwave into the plasma processingchamber to perform processing, wherein a microwave sealing member isprovided at a substrate-holding portion of the fixing means, a distance(D) between the microwave sealing member and a surface of the fixingmeans positioned in the plasma processing chamber is 0 to 55 mm, and adistance (L) between the microwave sealing member and an end portion ofthe processing gas supply member satisfies the following relationalexpressions:

A. in case of 0≦D<20L=(nλ/2+λ/8)−3+α

B. in case of 20≦D≦35L=(nλ/2+λ/8)−(−0.060 D²+4.2 D−57)+α

C. in case of 35<D≦55L=(nλ/2+λ/8)−(−0.030 D²+2.1 D−21)+α

where n is an integer, λ is a wavelength of the microwave, and α is afluctuation band in consideration of an influence and the like of thesubstrate on an electric field and is ±10 mm.

As described above, in the present invention, providing the microwavesealing member at a predetermined position below the holding member canprevent the microwave introduced into the plasma processing chamber fromleaking outside the chamber.

Furthermore, the processing chamber can be formed as the excellentresonating system by specifying a distance between the processing gassupply member end portion and the microwave sealing member. As a result,since an electric field intensity in the plasma processing chamberformed by the microwave can be improved and the electric field intensitydistribution can be stabilized, the processing gas can be evenlyprocessed into plasma. That is, the energy of the introduced microwavecan be efficiently utilized, and a uniform thin film can be formed onthe substrate of the processing target.

Moreover, there is provided a microwave plasma processing deviceaccording to the present invention having: fixing means for fixing asubstrate as a processing target on a central axis in a plasmaprocessing chamber; exhausting means for depressurizing the inside andoutside of the substrate; a metal processing gas supply member which ispresent in the substrate and forms a reentrant cylindrical resonatingsystem along with the plasma processing chamber; and microwaveintroducing means for introducing a microwave into the plasma processingchamber to perform processing, wherein a microwave sealing member isprovided at a substrate-holding portion of the fixing means, and aconnection position of the microwave introducing means is a positionwhere an electric field is weak in an electric field intensitydistribution formed in the plasma processing chamber.

As described above, in the present invention, since the electricalconsistency between the processing chamber and the microwave can beimproved by connecting the connection position of the microwaveintroducing means at a height of the weak-field position out of thefield intensity distribution formed in the plasma processing chamber byintroduction of the microwave, the electric field intensity distributionin the processing chamber is stabilized and efficiently acts on theprocessing gas, and hence the plasma can be efficiently and evenlygenerated. That is, since the energy of the introduced microwave can beefficiently utilized and generation of the plasma can be stabilized anduniformed, a uniform thin film can be formed on the substrate of theprocessing target.

In this case, it is preferable that a distance (D) between the microwavesealing member and a surface of the fixing means positioned in theplasma processing chamber is 0 to 55 mm, and a distance (H) between themicrowave sealing member and the connection position of the microwaveintroducing means satisfies a relationship of the following expression:H=L−(n ₂λ/2+λ/8−3)+β(mm)

[where n₂ is an integer satisfying n₂≦n₁−1, λ is a wavelength of themicrowave, β is a fluctuation band caused due to a dimension or the likeof the substrate and is ±10 mm, and L is a distance between themicrowave sealing member and the end portion of the processing gassupply member and satisfies the following relationships:

A. in case of 0≦D<20L=(n ₁λ/2+λ/8)−3+αB. in case of 20≦D≦35L=(n ₁λ/2+λ/8)−(−0.060 D²+4.2 D−57)+αC. in case of 35<D≦55L=(n ₁λ/2+λ/8)−(−0.030 D²+2.1 D−21)+α

where n₁ is an integer which is not smaller than 1, λ is a wavelength ofthe microwave, and α is a fluctuation band in consideration of aninfluence and the like of the substrate on an electric field and is ±10mm].

As described above, in the present invention, the excellent resonatingsystem can be formed in the processing chamber by providing themicrowave sealing member at a predetermined position and specifying adistance between the microwave sealing member and the processing gassupply member end portion. The height (H) obtained above the aboveexpression represents the field-weak position in the field intensitydistribution formed in the processing chamber when the distance (L)satisfies the above expression. Connecting the microwave introducingmeans at this height (H) can improve the electric field intensity in theprocessing chamber as a whole.

It is to be noted that the above expression is an expression obtained asa result of an experiment and a result of an analysis using a computerprogram.

Additionally, there is provided a microwave plasma processing deviceaccording to the present invention having: fixing means for fixing asubstrate as a processing target on a central axis in a plasmaprocessing chamber; exhausting means for depressurizing the inside andoutside of the substrate; a metal processing gas supply member which ispresent in the substrate and forms a reentrant cylindrical resonatingsystem along with the plasma processing chamber; and microwaveintroducing means for introducing a microwave into the plasma processingchamber to perform processing, wherein a plasma ignition gap is formedon an end surface side of the substrate-holding portion of the fixingmeans and the microwave sealing member is provided in the formed gap.

As described above, in the present invention, since providing the plasmaignition gap between the microwave sealing member and the end surface ofthe holding member can reduce the microwave output required for ignitionof the plasma, the plasma can be generated in a short time afterstarting introduction of the microwave.

In this case, it is preferable that driving means for relatively movingthe microwave sealing member and the substrate-holding portion to theplasma processing device forming the microwave reentrant cylindricalresonating system, and the microwave sealing member and thesubstrate-holding portion are relatively moved by this driving means toadjust the plasma ignition gap between the microwave sealing member andthe end surface of the substrate-holding portion.

As described above, in the present invention, a plasma emission starttime can be adjusted by relatively moving the microwave sealing memberand the substrate-holding portion and carrying out provision/eliminationof the plasma ignition gap at an arbitrary timing.

Further, there is provided a plasma processing gas supply memberaccording to the present invention which is a chemical plasma processinggas supply member comprising a porous pipe having an aperturedistribution in a lengthwise direction.

In this case, it is preferable that a reference area having a fixedaperture and a blowing quantity adjustment area having an aperturesmaller than that of the reference area are formed in a lengthwisedirection in the porous pipe.

Furthermore, it is possible to adopt a configuration in which theblowing quantity adjustment area is formed at an end portion.

As described above, in the present invention, when performing chemicalplasma processing, as a gas supply member (a gas supply pipe) whichsupplies a reactive gas into a predetermined processing area where asubstrate to be processed is arranged, the porous pipe having anaperture distribution in the lengthwise direction is used. That is, adistribution is provided to the aperture of a hole of the porous pipe ina lengthwise direction of the pipe, the gas blowing quantity adjustmentarea having a smaller aperture (or a larger aperture) than that of thereference area is formed in addition to the reference area having, e.g.,a predetermined aperture, and the porous pipe having the gas blowingquantity adjustment area formed at an appropriate position can bethereby used as the gas supply member in accordance with a plasmaprocessing device to be utilized, thereby performing the chemical plasmaprocessing.

For example, when a microwave is introduced into the plasma processingchamber of the plasma processing device and a source gas is suppliedfrom the gas supply pipe arranged in the plasma processing chamber toperform the chemical plasma processing, the plasma processing device hasan electric field intensity distribution inherent thereto, a thick filmis formed at a part where the electric field intensity is high, and athickness of a film formed at a part where the electric field intensityis low is small.

As described above, in the present invention, by inserting the porouspipe (the gas supply pipe) into the plasma processing chamber in such amanner that its gas blowing quantity adjustment area is placed at a partwhere the electric field intensity is large or small, occurrence ofirregularities in thickness mentioned above can be suppressed, and aprocessed film having an even thickness can be formed.

It is to be noted that the porous pipe can be formed of an arbitraryporous material, and it is possible to provide the porous pipe accordingto the present invention by forming a hole with a predetermineddistribution to, e.g., a non-porous metal pipe.

Moreover, there is provided a plasma processing gas supply memberaccording to the present invention comprising a gas supply pipe which isinserted into a container held in a plasma processing chamber into whicha microwave is introduced and supplies a reactive gas which is sued toform a CVD film on an inner surface of the container, wherein the gassupply pipe is sectionalized into two areas, i.e., an electric fieldintensity distribution stabilizing area and an end gas induction areawhich is positioned on an end side with respect to the electric fieldintensity distribution stabilizing area, at least a metal portion whichcommunicates with a shield wall constituting the plasma processingchamber and extends from a root portion to a boundary between theelectric field intensity distribution stabilizing area and the end gasinduction area in an axial direction is formed in the electric fieldintensity distribution stabilizing area, and the end gas induction areais formed of a non-metal material.

In this case, the gas supply pipe comprises the porous metal pipe andthe non-metal tubular end portion joined to the end thereof, the porousmetal pipe can form the electric field intensity stabilizing area, andthe non-metal tubular end portion can form the end gas induction area.

Additionally, the entire gas supply pipe is a non-metal porous pipe, ametal rod communicating with a shield wall constituting the plasmaprocessing chamber and extending from a root portion in an axialdirection extends inside the non-metal porous pipe, and the gas supplypipe is sectionalized into two areas, i.e., the electric field intensitydistribution stabilizing area and the end gas induction area by thismetal rod.

As described above, in the present invention, when performing thechemical plasma processing using microwaves, as the gas supply memberwhich supplies the reactive gas (the plasma processing gas) into acontainer held in the plasma processing chamber, there is used the gassupply pipe which is sectionalized in two areas, i.e., the electricfield intensity distribution stabilizing area and the end gas inductionarea positioned on the end side of the electric field intensitydistribution stabilizing area. According to such a gas supply member, inthe electric field intensity distribution stabilizing area, at least themetal portion communicating with the shield wall constituting the plasmaprocessing chamber is formed along the entire axial direction of thisarea. This metal portion is constituted to extend from a root portion ofthe gas supply pipe to a boundary with the end gas induction area, andthe gas supply pipe in this area comprises the metal porous pipe in thesimplest form. When a length of the electric field intensitydistribution stabilizing area in which such a metal portion is formed isset to have a fixed relationship with respect to a half-wavelength (λ/2)of the microwave used for the plasma processing, the plasma processingarea (the inside of the container) can be formed as the excellentresonating system, the electric field intensity of the plasma processingarea can be increased and, at the same time, the electric fieldintensity distribution along the axial direction of the container to beprocessed can be stabilized. Therefore, the reactive gas (the plasmaprocessing gas) supplied from the gas supply pipe into the container canbe efficiently and uniformly formed as plasma by forming theabove-described area, which is advantageous to formation of a filmhaving an even thickness.

The electric field intensity distribution area provides theabove-described advantages when its length is set to satisfy a fixedrelationship with respect to a half-wavelength (λ/2) of the microwave.Therefore, when the gas supply pipe is formed of the electric fieldintensity distribution stabilizing area only, since a length of the gassupply pipe cannot be arbitrarily adjusted, a position of the endportion is unavoidably apart from a bottom portion of the container,supply of the gas to the bottom portion of the container becomesinsufficient, and hence a vapor deposition film (a CVD film) having asufficient film thickness is hard to be formed. Thus, in the presentinvention, by forming the end gas induction area in which a pipe wall isconstituted of a non-metal material on the end side of this electricfield intensity distribution stabilizing area, a sufficient quantity ofgas can be supplied to the bottom portion of the container withoutaffecting the electric field intensity distribution. As a result, a CVDfilm having an even thickness can be formed on the container innersurface including the bottom portion.

Further, there is also a notable effect that using such a gas supplymember according to the present invention enables formation of a CVDfilm having an even thickness to a container in which a planarcross-sectional shape of a trunk portion is an axisymmetrical shape likea circular shape as well as a container in which a cross-sectional shapeof a trunk portion is a non-axisymmetrical shape like a rectangularshape.

Although the gas supply member (the gas supply pipe) is usually insertedalong a center of the axis of the container, since a gap between theinner surface of the container trunk portion wall and the gas supplymember is not even in the container in which a cross-sectional shape ofthe trunk portion is non-axisymmetrical, there is a problem that athickness of a CVD film to be formed varies depending on acircumferential position of the trunk portion wall inner surface. Thatis because the trunk portion inner wall has a part where a gap withrespect to the gas supply pipe is small and a part where the same islarge, and there is a tendency that the CVD film has a large thicknessat the part where the gap is small and the CVD film has a smallthickness at the part where the gap is large. Thus, in the presentinvention, using the gas supply pipe in which the predetermined end gasinduction area is formed at an end of the electric field intensitydistribution stabilizing area can effectively suppress irregularities inthickness along the circumferential direction in such anon-axisymmetrical container.

In the present invention, the fact that irregularities in thicknessalong the circumferential direction in the non-axisymmetrical containercan effectively suppressed has been experimentally confirmed, and thepresent inventors assumes that its reason is as follows. That is, an endposition of the gas supply member is conventionally restricted by afunction of a half-wavelength of the microwave in order to stabilize theelectric field intensity, and a large gap is formed between this endposition and the bottom portion of the container. In the presentinvention, in order to form the predetermined end gas induction area atthe end portion of the gas supply member (the gas supply pipe), the gapbetween the gas supply pipe and the container bottom portion is narrowedby an amount corresponding to this area. It can be considered that thereactive gas sprayed on the surface of the bottom portion flows in thecircumferential direction as a result of narrowing the gap, the gaswhich has moved in the circumferential direction flows into the partwhere the gap between the gas supply pipe and the trunk portion wall islarge in particular and irregularities in thickness in thenon-axisymmetrical container in the circumferential direction can bethereby effectively suppressed.

As described above, according to the gas supply member of the presentinvention, the vapor deposition film having a sufficient thickness canbe likewise formed at the container bottom portion by the plasma CVDmethod using a microwave, and the vapor deposition film having an eventhickness can be formed on the entire inner surface even in a containerin which a planar shape of a trunk portion is either axisymmetrical ornon-axisymmetrical.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic arrangement plan of a microwave plasma processingdevice according to a first embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a plasma processingchamber of the microwave plasma processing device according to the firstembodiment of the present invention;

FIG. 3 is a schematic cross-sectional view of a plasma processingchamber of a microwave plasma processing device according to a secondembodiment of the present invention;

FIG. 4 is a partially enlarged cross-sectional view of bottle fixingmeans of the microwave plasma processing device according to the secondembodiment of the present invention;

FIG. 5 is a graph showing a relationship between a size G of an ignitiongap and a time from introduction of a microwave to plasma emission and arelationship between the size G of the gap and an intensity of themicrowave (a reflected wave) which has returned from the plasmaprocessed chamber without being effectively used for plasma duringplasma emission in the microwave plasma processing device according tothe second embodiment of the present invention;

FIG. 6 is a graph showing a relationship between a control voltage Ewhich is used to set an output of the microwave based onpresence/absence of the ignition gap and a time from introduction of themicrowave to plasma emission in the microwave plasma processing deviceaccording to the second embodiment of the present invention;

FIG. 7 is a view illustrating a control example of the microwave outputand the ignition gap in a plasma processing method using the microwaveplasma processing device according to the second embodiment of thepresent invention;

FIG. 8 is a view illustrating another control example of the microwaveoutput and the ignition gap in the plasma processing method using themicrowave plasma processing device according to the second embodiment ofthe present invention;

FIG. 9 is a cross-sectional side view showing a typical example of aplasma processing gas supply member according to a third embodiment ofthe present invention;

FIG. 10 is a cross-sectional side view showing another preferred exampleof the plasma processing gas supply member according to the thirdembodiment of the present invention;

FIG. 11 is a graph showing a relationship between a thickness of aplasma processing film formed by microwave glow discharge and a heightfrom a bottle bottom portion when a source gas is supplied into thebottle by using the plasma processing gas supply member according to thethird embodiment of the present invention;

FIG. 12 is a cross-sectional side view showing a typical example of aplasma processing gas supply member according to a fourth embodiment ofthe present invention;

FIG. 13 is a cross-sectional side view showing another preferred exampleof the plasma processing gas supply member according to the fourthembodiment of the present invention;

FIG. 14 is a cross-sectional plan view of a container trunk portion towhich the plasma processing gas supply member according to the fourthembodiment of the present invention is applied;

FIG. 15 is a graph showing an experimental result-1 (a film thicknessdistribution in a bottle height direction) using the plasma processinggas supply member according to the fourth embodiment of the presentinvention; and

FIG. 16 is a graph showing an experimental result-2 (a film thicknessdifference in a bottle circumferential direction) using the plasmaprocessing gas supply member according to the fourth embodiment of thepresent invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Preferred embodiments of a microwave plasma processing device and aplasma processing gas supply member according to the present inventionwill now be described hereinafter. It is to be noted that the presentinvention is not restricted to these embodiments.

First Embodiment

First, a microwave plasma processing device according to a firstembodiment of the present invention will be described with reference toFIGS. 1 and 2.

This embodiment is an embodiment in which the microwave plasmaprocessing device according to the present invention is applied tobottle inner surface processing. As a bottle in this embodiment, thereis a biaxial-drawing-blow-molded bottle formed of polyester such aspolyethylene terephthalate.

[Microwave Plasma Processing Device]

FIG. 1 is a schematic arrangement plan of the microwave plasmaprocessing device according to this embodiment.

A vacuum pump 2 which performs emission of a gas in a processing chamber1 and maintains the inside of this chamber in a depressurized state isconnected with the plasma processing chamber 1 through an exhaust pipe3. Further, a microwave oscillator 4 is connected through a waveguidetube 5 which is microwave introducing means.

The microwave oscillator 4 is not restricted in particular as long as itcan oscillate a microwave which acts on a processing gas to produce glowdischarge, and a commercially available one can be used.

The waveguide tube 5 is the microwave introducing means whichefficiently transmits a microwave oscillated from the microwaveoscillator 4 into the processing chamber 1, and one suitable for awavelength of the microwave to be used can be utilized. As the microwaveintroducing means, a coaxial cable can be used in place of the waveguidetube.

It is to be noted that the three stub tuner 6 may be provided in orderto adjust a microwave reflection quantity from the processing chamber atthe minimum level. However, the tuner 6 just forcibly reduces areflection quantity as much as possible, and cannot form an excellentresonating system inside the plasma processing chamber 1. That is, theexcellent resonating system can be formed inside the plasma processingchamber 1 only by using the plasma processing device according to thepresent invention which will be described below, and efficientprocessing is possible without using adjusting means such as a tuner inthis case.

[Plasma Processing Chamber]

FIG. 2 is a schematic cross-sectional view of the plasma processingchamber in the microwave plasma processing device according to thisembodiment.

The plasma processing chamber 1 comprises a hollow chamber 11 mounted ona base 10, a detachable hood 12 positioned at an upper portion of thechamber 11, and bottle fixing means 14 which fixes a bottle 13 as aprocessing target. The waveguide tube 5 which transmits the oscillatedmicrowave from the microwave oscillator 4 into the plasma processingchamber 1 is connected to a side surface of the chamber 11.

The plasma processing chamber 1 forms a so-called microwave reentrantcylindrical resonating system. That is, the cylindrical chamber 11 formsthe plasma processing chamber 1, and an electroconductive processing gassupply member 15 is provided on an axis of this chamber in such a mannerthat an end portion of this member does not reach the hood 12.

The bottle 13 has a mouth portion 131 held by the bottle fixing means14, and is fixed on the axis of the chamber 11. The processing gassupply member 15 is inserted into the bottle 13. In this state, thevacuum pump 2 forms a vacuum inside and outside the bottle 13, aprocessing gas is supplied from the processing gas supply member 15inserted in the central part of the bottle 13, and a microwave issupplied from the side surface of the processing chamber 1.

The bottle fixing means 14 is positioned below the chamber 11, and has abottle holding portion 141 which holds the mouth portion 131 of thebottle, an exhaust opening 142 which is used to depressurize the insideof the bottle 13 and a microwave sealing member 143 which is positioneddirectly below the bottle holding portion 141 and provided to cover theexhaust opening 142.

Furthermore, the bottle fixing means 14 is connected with a rod (notshown) capable of moving up and down. As a result, when the bottle 13 isattached to/detached from the bottle fixing means 14, the hood 12 isopened and the rod is moved up, thereby moving the bottle 13 (the fixingmeans 14) to the outside of the chamber 11.

The processing gas supply member 15 is inserted in such a manner that itpierces the bottle fixing means 14 coaxially with the chamber 11 and ispositioned in the bottle 13.

The processing gas supply member 15 is connected with a processing gassupply device (not shown) through a processing gas supply path 152 sothat the gas can be supplied at a predetermined speed.

As a material forming the processing gas supply member 15, it ispossible to use a metal such as SUS, Al, Ti or the like. For example, incase of forming a chemical vapor deposition film on the inner surface ofthe bottle 13, using a porous metal is preferable since a resulting thinfilm layer can have the excellent homogeneity and the improved ductilityand flexibility, and the productivity can be also improved.

Although one or more gas discharge holes are formed through theprocessing gas supply member 15, positions, a size and the number of theholes can be arbitrarily set.

It is preferable that the same type of film as the film formed on theinner surface of the bottle 13 by plasma processing is formed on thesurface of the processing gas supply member 15.

A gap 16 is provided between the chamber 11 and the bottle fixing means14 in order to depressurize the inside of the processing chamber 1, andconnected with an exhaust pipe 3 through the base 10. Likewise, theexhaust opening 142 provided to the bottle fixing means 14 is alsoconnected with the exhaust pipe 3 in order to depressurize the inside ofthe bottle 13.

The microwave sealing member 143 is provided in order to prevent themicrowave from leaking outside the processing chamber 1 from the exhaustopening 142, and it is a member which has an effect of trapping in theprocessing chamber 1 the microwave introduced into this chamber. As thismicrowave sealing member 143, it is possible to use one which cantransmit a gas therethrough without obstructing a depressurization stepin the bottle 13 and can cut off the microwave, e.g., a wire gauzeformed of SUS, Al, Ti or the like.

Moreover, in this embodiment, it is preferable to set a distance (D)from an upper surface 144 of the bottle fixing means 14 to the microwavesealing member 143 to 0 mm to 55 mm, and more preferably, 20 mm to 50mm. When the distance (D) exceeds 55 mm, since the plasma processingchamber does not form a resonating system, an electric field intensityin the plasma processing chamber is reduced, and generation of plasma isdifficult.

It is to be noted that, in a conventional microwave processing devicedescribed in PCT National Publication No. 2001-518685, the microwavecannot be satisfactorily trapped even if the microwave is introducedinto the processing chamber 1 since the microwave partially leaksoutside the chamber from a connection portion with the exhaust openingor the like, and the processing chamber 1 is incomplete as a resonatingsystem. Therefore, an electric field intensity distribution formed inthe processing chamber 1 by the introduced microwave is unstable,generation of plasma is consequently unstable and uneven, resulting inthe state with the deteriorated energy efficiency.

In this embodiment, setting the microwave sealing member 143 at apredetermined position can prevent the microwave introduced into theprocessing chamber 1 from leaking outside the chamber, thereby improvingthe utilization efficiency of the energy of the introduced microwave.

That is, the microwave sealing member 143 is determined as a reference,and a distance from this member to each constituent member is specified,thereby facilitating optimization in the processing chamber 1.

First, in this embodiment, a distance (L) from the microwave sealingmember 143 to a gas supply member end portion 151 is set to satisfy thefollowing relationships.

A. In case of 0≦D<20L=(nλ/2+λ/8)−3+α

B. In case of 20≦D≦35.L=(nλ/2+λ/8)−(−0.060 D²+4.2 D−57)+α

C. In case of 35<D≦35L=(nλ/2+λ/8)−(−0.030 D²+2.1 D−21)+α

where n is an integer, λ is a wavelength of the microwave, and α is ±10mm which is a fluctuation band in consideration of an influence and thelike of the substrate on an electric field.

Additionally, in this embodiment, it is preferable for a distance (H)between the microwave sealing member 143 and a connection position ofthe microwave introducing means to satisfy a relationship of thefollowing expression.H=L−(n ₂λ/2+λ/8−3)+β(mm)

where n₂ is an integer satisfying n₂≦n₁−1, λ is a wavelength of themicrowave, β is ±10 mm which is a fluctuation band caused due to adimension or the like of the substrate, and L is a distance between themicrowave sealing member and the processing gas supply member endportion and satisfies the following relationship.

A. In case of 0≦D<20L=(n ₁λ/2+λ/8)−3+αB. In case of 20≦D≦35L=(n ₁λ/2+λ/8)−(0.060 D²+4.2 D−57)+αC. In case of 35<D≦55L=(n ₁λ/2+λ/8)−(0.030 D²+2.1 D−21)+α

where n₁ is an integer not less than 1, λ is a wavelength of themicrowave, and α is ±10 mm which is a fluctuation band in considerationof an influence and the like of the substrate on an electric field.

Each of the above expressions is an expression obtained as a result ofan experiment and a result of analysis using a computer program.

H obtained from this expression indicates a part corresponding to a node171 of an electric field intensity distribution 17 formed on theprocessing gas supply member 15 by introducing the microwave, i.e., apart having the low electric field intensity (see FIG. 2). Connectingthe waveguide tube 5 at the same height as this part can minimize areflected wave which flows backward through the waveguide tube 5 withoutbeing consumed in the processing chamber 1. That is, the introducedmicrowave can be efficiently utilized for formation of plasma from theprocessing gas.

Further, when the distance (L) satisfies the above-described relationalexpressions, the electric field intensity formed in the processingchamber 1 by the introduced microwave can be entirely improved, and anelectric field intensity distribution can be stabilized. Therefore, theenergy of the introduced microwave can be efficiently used forgeneration of the plasma, and the state of the plasma is stable anduniform, thereby evenly processing the surface of the bottle innersurface.

When a microwave having a frequency of, e.g., 2.45 GHz is used, awavelength of this microwave is approximately 120 mm. Assuming that thedistance (D) from the upper surface 144 of the bottle fixing means 14 tothe microwave sealing member 143 is 30 mm, a value of the distance (L)which satisfies the above-described expression and with which the stableplasma can be obtained is 60±10 mm, 120±10 mm, 180±10 mm or the like.Furthermore, it is preferable to select a length with which the endportion 151 of the processing gas supply member can be placed at aposition close to the bottle bottom portion 132 as much as possible fromthese values of L in accordance with a shape, a size and others of thebottle 13 as a processing target since a vapor deposition film having aneven thickness can be formed on the entire surface of the bottle 13.

Moreover, the distance (H) between the microwave sealing member 143 andthe connection position of the microwave introducing means (thewaveguide tube 5) at this moment is 48 mm, 108 mm, 168 mm or the like.

It is preferable to select a length with which the end portion 151 ofthe processing gas supply member can be placed at a position close tothe bottle bottom portion 132 as much as possible from these values of Hand L in accordance with a shape, a size and others of the bottle 13 asa processing target since a vapor deposition film having an eventhickness can be formed on the entire surface of the bottle 13.

For example, as the distance (L), 170 to 190 mm is preferable for theprocessing of a general bottle container whose capacity is 500 mm, and110 to 130 mm is preferable for the processing of a bottle containerwhose capacity is 350 mm.

It is to be noted that although the number of the connection position ofthe waveguide tube 5 is one in this embodiment, the waveguide tube 5 maybe connected at a plurality of positions H satisfying theabove-described expression.

Additionally, it is preferable for a distance (S) from the bottle bottomportion 132 to a hood lower surface 121 to fall within a range of 5 mmto 150 mm. Since setting this distance within this range can improve theconsistency of the chamber 11 and the microwave, the electric fieldintensity distribution in the processing chamber 1 can be furtherstabilized. In particular, a range of 30 mm to 100 mm is preferable.

Further, it is preferable for an internal diameter (φ) of the processingchamber 1 to fall within a range of 40 mm to 150 mm. By setting theinternal diameter of the processing chamber 1 within this range,electric field concentration effect toward the center of the processingchamber 1 can be demonstrated, which is more effective. In particular, arange of 65 mm to 120 mm is preferable.

[Microwave Plasma Processing Method]

A bottle processing method using the above-described microwave plasmaprocessing device according to this embodiment will now be concretelydescribed.

First, the bottle 13 is fixed to the bottle fixing means 14. At thismoment, the hood 12 has been already removed from the chamber 11, andthe bottle fixing means 14 has moved up in the chamber 11 by the rod(not shown) to be placed at the upper portion of the chamber 11.

In this state, the mouth portion of the bottle 13 is held by the bottleholding portion 141, the rod is moved down to arrange the mouth portionat a predetermined position of the bottle fixing means 14. Then, thehood 12 is closed to seal the inside of the chamber 11, thereby enteringthe state shown in FIG. 2.

Subsequently, the vacuum pump 2 is driven to provide the depressurizedstate in the bottle 13. At this time, in order to avoid deformation ofthe bottle 13 by an external pressure, it is also possible to providethe depressurized state in the plasma processing chamber 1 outside thebottle by the vacuum pump 2.

It is good enough to perform depressurization in the bottle 13 to theextent that glow discharge is produced when the processing gas isintroduced and the microwave is introduced. Specifically, performingdepressurization within a range of 1 to 500 Pa, especially 5 to 200 Pais preferable for an improvement in the efficiency of the plasmaprocessing.

On the other hand, depressurization in the plasma processing chamber 1outside the bottle 13 is carried out to the extent that glow dischargeis not generated even when the microwave is introduced, e.g., 1000 to10000 Pa.

After reaching this depressurized state, the processing gas is suppliedinto the bottle 13 by the processing gas supply member 15.

Although a processing gas supply quantity varies depending on asuperficial area of the bottle 13 as a processing target or a type ofthe processing gas, it is preferable to supply the processing gas with,e.g., a flow quantity of 1 to 500 cc/min, especially 2 to 200 cc/min ina standard state per container.

When forming a thin film by the reaction of a plurality of processinggases, one processing gas can be excessively supplied. For example, itis preferable to excessively supply an oxygen gas as compared with asilicon source gas in case of forming a silicon oxide film, and nitrogenor ammonia can be excessively supplied as compared with a metal sourcegas in case of forming a nitride film.

Subsequently, a microwave is introduced into the plasma processingchamber 1 through the waveguide tube 5. As the microwave, the microwaveis not restricted in particular as long as it can act on the processinggas to generate glow discharge, but it is preferable to use a microwavehaving 2.45 GHz, 5.8 GHz or 22.125 GHz as a frequency which is allowedfor an industrial use.

Although an output of the microwave differs depending on a superficialcontent of the bottle 13 or a type of the processing gas, it ispreferable to introduce the microwave in such a manner that 50 to 1500W, especially 100 to 1000 W can be achieved per bottle, for example.

The microwave introduced into the processing chamber 1 provides theprocessing gas with the high-energy state, and forms a plasma state. Theprocessing gas formed as the plasma acts on and is deposited on theinner surface of the bottle 13, thereby forming a coating film.

Although a processing time in this example varies depending on asuperficial content of the bottle 13, a thickness of a thin film to beformed, a type of the processing gas and others and hence it cannot begenerally specified, a time of one second or more is required per bottlein order to stabilize the plasma processing, for example. A shorterprocessing time is preferable in terms of the cost.

After performing the plasma processing, supply of the processing gas andintroduction of the microwave are stopped, and air is graduallyintroduced through the exhaust pipe 3 so that the inside and outside ofthe bottle 13 return to an ordinary pressure. Thereafter, the hood 12 isremoved, the bottle fixing means 14 is moved up, and the bottlesubjected to the plasma processing is removed outside the plasmaprocessing chamber 1.

[Bottle Container as Processing Target]

In this embodiment, as the bottle which can be processed, there is abottle containing plastic as a raw material.

As plastic, there are a known thermoplastic resin, e.g., low-densitypolyethylene, high-density polyethylene, polypropylene, polyolefin suchas poly1-butene or poly4-methyl-1-pentene; a random copolymer or a blockcopolymer consisting of -olefin such as ethylene, propylene, a-butene or4-methyl-1-pentene; an ethylene vinyl compound copolymer such as anethylene vinyl acetate copolymer, an ethylene vinyl alcohol copolymer oran ethylene chloroethene copolymer; a styrene-based resin such aspolystyrene, a acrylic nitrile styrene copolymer, ABS or a-methylstyrene styrene copolymer; a polyvinyl compound such aspolyvinylchloride, polyvinylidene chloride, a chloroethene vinylidenechloride copolymer, polyacrylic methyl or polymethacrylic methyl;polyamide such as nylon 6, nylon 6-6, nylon 6-10, nylon 11 or nylon 12;thermoplastic polyester such as polyethylene terephthalate, polybutyleneterephthalate or polyethylene naphthalat; polycarbonate, polyphenyleneoxide, polylactic acid and others. Each of these resin may be solelyused, or two or more types of these resins may be mixed or multi-layeredto be used. Further, it is possible to use a multi-layer plasticcontainer in which an oxygen absorbing material or various kinds ofmoisture or oxygen barrier material are arranged as an intermediatelayer.

Furthermore, it is possible to apply to various kinds of glass, ceramicor porcelain; oxide-based ceramic such as alumina, silica, titania orzirconia; nitride-based ceramic such as aluminium nitride, boronnitride, titanium nitride, silicon nitride or zirconium nitride;carbide-based ceramic such as silicon carbide, boron carbide, tangstencarbide or titanium carbide; boride-based ceramic such as siliconboride, titanium boride or zirconium boride; high-dielectric ceramicsuch as rutile, magnesium titanate, zinc titanate or rutile-lanthanumoxide; piezoelectric ceramic such as lead titanate; and various kinds offerrite.

It is to be noted that the present invention is not restricted to theabove-described embodiment, and it can be applied to processing of asubstrate having a shape like a general container or a pipe such as acup other than the bottle.

[Processing Gas]

As the processing gas, various kinds of gases can be used in accordancewith purposes of the plasma processing.

For example, for the purpose of improving gas barrier properties of aplastic container, a compound containing atoms, molecules or ionsconstituting a thin film is set in a gas phase state to be used togetherwith an appropriate carrier gas. As a compound which is a raw materialof a thin film, it must have the high volatility.

As a concrete example, in order to form a carbon film or a carbide film,carbon hydrides such as metane, ethane, ethylene or acetylene are used.

In order to form a silicon film, silicon tetrachloride, silane, anorganic silane compound, an organic siloxane compound or the like isused.

An oxygen gas is used for formation of an oxide film, and a nitrogen gasor an ammonia gas is used for formation of a nitride film.

Further, for the purpose of surface property modification of plastics abridge configuration can be introduced to the surface of plastic byusing carbon dioxide, or the same characteristics as those ofpolytetrafluoroethylene, e.g., the non-adhesiveness, a low frictioncoefficient, the heat resistance or the chemical resistance can beprovided to the plastic surface by using a fluorine gas.

Besides, it is possible to use a halogenide (a chloride) or an organicmetal compound of, e.g., titanium, zirconium, tin, aluminum, yttrium,molybdenum, tungsten, gallium, tantalum, niobium, iron, nickel, chromeor boron.

Two or more types of these processing gases can be appropriatelycombined and used in accordance with a chemical composition of a thinfilm to be formed.

On the other hand, as the carrier gas, argon, neon, xenon, hydrogen orthe like is appropriate.

As described above, according to the microwave plasma processing deviceof this embodiment, the microwave sealing member is provided at apredetermined position of the substrate-holding portion of the fixingmeans, a length of the processing gas supply member is specified withthis position being determined as a reference, the connection positionof the microwave introducing means is specified, and hence theprocessing gas can be evenly turned into plasma with the excellentenergy efficiency, thereby forming an even thin film on the targetsubstrate to be processed.

Embodiment

Excellent effects of the microwave plasma processing device according tothis embodiment will now be described with reference to the followingexperimental examples. Incidentally, it is needless to say that themicrowave plasma processing device according to the present invention isnot restricted to the following examples.

Experimental Conditions

As a base material which is a processing target, a PET bottle having amouth portion nominal diameter of φ28 mm was used.

An organic silicon compound gas ad an oxygen gas were used as theprocessing gas, and gas flow quantities were determined as 2 sccm and 20sccm, respectively.

Degrees of vacuum inside and outside the bottle at the time of plasmaprocessing were adjusted to be 20 Pa and 7000 Pa so that plasma can beexcited only in the bottle when the microwave is supplied.

The microwave was oscillated by using a commercially available microwavepower supply (2.45 GHz), and it was supplied into the plasma processingchamber with an output of 500 W. It is to be noted that a plasmaprocessing time was determined as 10 seconds after plasma ignition.

EXPERIMENTAL EXAMPLE 1

In the microwave plasma processing device shown in FIG. 2, the plasmaprocessing was conducted with respect to PET bottles having innercapacities of 500 ml (Experiments 1-1 to 1-3) and 350 ml (Experiment1-4) by using a chamber 11 having a dimension with which a distance (S)between a bottom portion 132 of the bottle having an internal diameterof φ90 mm and an inner capacity of 500 ml and a hood lower surface 121is 75 mm, bottle fixing means 14 and a processing gas supply member 15with which a distance (D) from an upper surface 144 of the bottle fixingmeans 14 to a microwave sealing member 143 and a distance (L) from themicrowave sealing member 143 to a gas supply member end portion 151become values shown in Table 1.

As an evaluation, whether plasma emission is possible and a reflectionintensity of the microwave which can be considered to be returnedwithout being used for the plasma processing were checked.

Furthermore, in regard to conditions under which the processing wasperformed, oxygen barrier properties were checked by using Ox-tranmanufactured by Mocon in order to judge the performance of a coatingfilm formed by the processing.

Table 1 shows an evaluation result. TABLE 1 Possibility/ impossibilityReflected D L of plasma wave Barrier (mm) (mm) emission intensity Wproperties Experiment 30 200 X — — 1-1 190 Δ (Emission is 120  X weak)180 ◯ 30 ◯ 170 Δ (Emission is 130  X weak) 160 X — — 140 X — — 120 ◯ 35Δ 100 X — — Experiment 60 200 X — — 1-2 190 X — — 180 X — — 170 X — —160 X — — Experiment 20 180 Δ (Emission is 90 Δ 1-3 weak) 30 ◯ 30 ◯ 40 ◯50 ◯ 50 Δ (Emission is 145  Δ weak) Experiment 30 130 Δ 105  Δ 1-4 120 ◯40 ◯ 110 Δ 95 Δ*Oxygen barrier properties (achievement of a target value) ◯:satisfactory (within a practical range) Δ: rather insufficient X:definitely insufficient

In Experiment 1-1, since D is 30 mm, L satisfying the expressionL=(nλ/2+λ/8)−(−0.060 D²+4.2 D−57) is 60 mm±α, 120 mm±α, 180 mm±α or thelike.

It was confirmed that plasma emission is generated and a thin film wasable to be formed on the bottle when D and L satisfy this condition.That is, it was confirmed that the plasma processing with respect to thebottle is possible within a range of 180 mm±10 mm.

In this experimental example, the bottle container having theexcellent-barrier properties was obtained in an area where α is ±5 mm,in particular.

Based on Experiment 1-2, it was confirmed that plasma emission is notgenerated irrespective of a value of L when D becomes large.

It was confirmed from Experiment 1-3, it was confirmed that the plasmaprocessing can be performed assuming that D=20 to 50 mm and L=175 to 185mm. In particular, the result was good when a value of D is 25 to 45 mm.This value of L is suitable for the bottle having the capacity of 500ml.

Further, it was confirmed from Experiment 1-4 that the plasma processingcan be performed even when a value of L is set to 110 mm to 130 mmsuitable for the bottle having the capacity of 350 ml. It was found thatstable plasma emission with the good energy efficiency can be obtainedand a bottle with the excellent properties can be acquired by theprocessing when a value of D is set to 115 to 125 mm in particular.

EXPERIMENTAL EXAMPLE 2

A bottle was set in the same device as that of Experimental Example 1,the dimension (D) was set to values shown in Table 2, and the dimension(L) with which the reflection intensity of the microwave becomes minimumwith respect to each dimension (D) was checked by using a PET bottlehaving a capacity of 500 ml.

Furthermore, excellent combinations of the dimensions (D) and (L) wereobtained by using commercially available spread sheet software based onthis result.

Table 2 shows a result. TABLE 2 D 20 25 30 35 40 45 50 (mm) L 192 185180 179 180 182 186 (mm)

Second Embodiment

A microwave plasma processing device according to a second embodiment ofthe present invention will now be described with reference to FIGS. 3and 4.

FIG. 3 is a schematic cross-sectional view of a plasma processingchamber in the microwave plasma processing device according to thisembodiment, and FIG. 4 is a partially enlarged cross-sectional view ofbottle fixing means.

As shown in these drawings, this embodiment has a configuration in whichan arbitrary plasma ignition gap 146 is provided between the microwavesealing member 143 and the end surface 141-1 of the bottle holdingportion of the microwave plasma processing device according to the firstembodiment and a size of this gap can be adjusted.

Therefore, any other configurations, functions, effects and advantagesare the same as those of the microwave plasma processing devicedescribed in conjunction with the first embodiment.

[Plasma Ignition Gap]

That is, in the microwave plasma processing device according to thisembodiment, a sealing member fixing frame 145 is inserted in an axialdirection at the lower portion of bottle fixing means 14 so that thisframe can independently move in a longitudinal direction in the bottlefixing means 14. This sealing member fixing frame 145 is moved by usinga non-illustrated cylinder or the like. By moving the sealing memberfixing frame 145 in this manner, the arbitrary plasma ignition gap 146is provided between the microwave sealing member 143 and the end surface141-1 of the bottle holding portion and a size of this gap is adjusted.

It is to be noted that the plasma ignition gap 146 is adjusted by movingthe sealing member fixing frame 145 in this embodiment, but the presentinvention is not restricted thereto, and the bottle fixing means 14 maybe Moved, or both the sealing member fixing frame 145 and the bottlefixing means 14 may be moved to adjust the plasma ignition gap 146.

[Effect of Plasma Ignition Gap]

The effect of the plasma ignition gap 146 in this embodiment will now bedescribed.

FIG. 5 is a graph showing a relationship between a size G of theignition gap 146 and a time from introduction of the microwave to plasmaemission and a relationship between the size G of the gap 146 and anintensity of the microwave (a reflected wave) which has returned fromthe plasma processing chamber 1 without being effectively used in plasmaemission in the microwave plasma processing device according to thisembodiment.

In a state where the ignition gap 146 is not provided between themicrowave sealing member 143 and the end surface 141-1 of the bottleholding portion 141, the reflected wave is small and the conditions aregood in terms of the energy efficiency of the plasma, but approximatelynine seconds were required from start of introduction of the microwaveto plasma emission, and this time varied each time. On the contrary,when the ignition gap 146 was provided, approximately one second wasrequired from start of introduction of the microwave to plasma emission,the time was greatly reduced and rarely varied each time.

FIG. 6 is a graph showing a relationship between a control voltage E (V)which is used to set an output (W) of the microwave and a time fromintroduction of the microwave to plasma emission in accordance withpresence/absence of the ignition gap 146 in the microwave plasmaprocessing device according to this embodiment.

An output control voltage of the microwave which is not smaller than 0.4V is required in order to generate plasma emission when the ignition gap146 is not provided between the microwave sealing member 143 and the endsurface 141-1 of the bottle holding portion 141, but plasma emission canbe started even at 0.15 V when the ignition gap 146 is provided.

It is to be noted that measurement values shown in FIGS. 5 and 6 aremeasurement results obtained when a chamber diameter is φ90 mm, a lengthof the processing gas supply member is 180 mm, a degree of vacuum in thebottle is 20 Pa and a mixed gas of oxygen and hexamethyldisiloxane(HMDSO) was supplied as the processing gas in such a microwave plasmaprocessing device as shown in FIG. 3 (and FIG. 4).

Moreover, it was assumed that an output control voltage of the microwaveis 0.35 V in the measurement of a time to plasma emission shown in FIG.5, and it is 1.6 V in the measurement of the reflected wave.

When the ignition gap 146 is provided in this manner, the microwaveoutput required for plasma ignition can be greatly reduced, and the timefrom introduction of the microwave to plasma emission can beconsiderably shortened.

Although the reason why the emission lower limit output can be reducedby provision of the ignition gap 146 is not known exactly, it can beconsidered that the microwave introduced into the plasma processingchamber 1 concentrates in the ignition gap 146, an electric fieldintensity in this part is thereby locally increased, and hence thisstrong electric field acts on the processing gas to form the plasma.

In this embodiment, it is preferable for the ignition gap 146 betweenthe microwave sealing member 143 and the end surface 141-1 of the bottleholding portion 141 to be 0.05 mm to 10 mm. When this gap is smallerthan 0.05 mm, the definite ignition gap 146 cannot not assured dependingon mechanical dimension accuracies, and the time from introduction ofthe microwave to start of plasma emission (an induction time) cannot beshortened in some cases. When this gap is larger than 10 mm,concentration of the microwave in the ignition gap 146 is hardlygenerated, and the microwave may possibly leak outside the processingchamber 1 in some cases. In particular, 0.2 to 5 mm is preferable.

[Microwave Plasma Processing Method]

A bottle processing method using the microwave plasma processing deviceaccording to this embodiment will now be described.

First, each of processing of fixing the bottle 13 to the bottle fixingmeans 14, depressurization processing of the bottle 13 and the plasmaprocessing chamber 1 and processing of supplying the processing gas intothe bottle 13, the same processing as that in the first embodiment iscarried out under the same conditions.

Subsequently, the microwave is introduced into the plasma processingchamber 1 through the waveguide tube 5.

FIG. 7 is a view illustrating a control example of the microwave outputand the ignition gap in the plasma processing method according to thisembodiment.

First, in a state where the ignition gap 146 is provided, introductionof the microwave is started (t1). Introduction of the microwave in thisexample is carried out at a low output (Mw1).

Generally, an output of a set value is not oscillated immediately afterstart of introduction of the microwave, and a rising set output isslowly reached as shown in FIG. 7. In order to start plasma emission,the microwave which is not smaller than a fixed output must beintroduced (see FIG. 6). When the microwave is introduced into theplasma processing chamber 1, plasma emission is generated after aninduction time (t2).

In this embodiment, since the ignition gap 146 is provided at the timeof plasma ignition, an output of the microwave required for plasmaignition can be lowered, and the induction time can be set to the stableminimum necessary time (see FIG. 6).

It can be considered that these reductions are possible because theintroduced microwave concentrates around the ignition gap 146 betweenthe microwave sealing member 143 and the bottle holding portion endsurface 141-1, the energy density in this part is thereby increased, andhence the processing gas can efficiently have the high energy to formthe plasma state.

After plasma emission, it is preferable to move up the sealing memberfixing frame 145 in the longitudinal direction to eliminate the ignitiongap 146 between the microwave sealing member 143 and the end surface141-1 of the bottle holding portion. When the ignition gap 146 is notprovided, since a quantity of the reflected wave is minimum (see FIG.5), the utilization efficiency of the microwave is high, and an electricfield intensity distribution formed in the microwave processing chamber1 is also optimized. Therefore, a film formed on the inner surface ofthe bottle 13 becomes homogenous.

It is to be noted that an output of the microwave is maintained in alow-output state during a predetermined time (a holding time) even afterplasma ignition. A layer aboundingly containing organic components canbe formed on the bottle 13 by performing the plasma processing in thelow-output state.

For example, when an organic silicon compound is used as the processinggas, it is considered that a silicon oxide film is formed through thenext reaction paths.

(a) Extraction of hydrogen: SiCH₃→SiCH₂.

(b) Oxidization: SiCH₂.→SiOH

(c) Condensation: SiOH→SiO

Since the microwave with a relatively high output must be introduced forplasma emission in the prior art, a state of plasma is a high-outputstate from start of plasma emission. Therefore, the reaction is made allat once to the stage of the above-described reaction formula (c), asilicon oxide film layer having the poor flexibility is thereby directlyformed on the surface of the bottle 13, and the adhesiveness between thebottle 13 and the silicon oxide film layer is low.

On the contrary, in the present embodiment, since the plasma can beignited by using the low-output microwave, and the plasma emission canbe thereafter maintained with the excellent energy efficiency at a lowoutput, the SiCH₂. radials generated at the stage of the reactionformula (a) react with each other, and a thin film consisting of anorganic silicon compound polymer is formed on the bottle 13.

Since this thin film has the flexibility and demonstrates the excellenteffect as a binder of the bottle 13 and a silicon oxide film formed at asubsequent step, thereby forming a thin film layer with the goodadhesiveness on the bottle 13.

Although the output (Mw1) of the microwave in a low-output state variesdepending on a superficial content of the bottle 13 or a type of theprocessing gas, it is preferable to introduce the microwave so that 30to 100 W is provided per bottle, for example. Further, a holding time of0.1 second to 5 seconds is preferable.

After elapse of the holding time, the microwave with a high output isintroduced (Mw2), and processing based on the plasma in a high-outputstate is carried out. As a result, in case of, e.g., an organic siliconcompound, a hard silicon oxide film having the excellent gas barrierproperties obtained by the reaction formula (c) is formed.

Although an output (Mw2) of the microwave in a high-output state variesdepending on a superficial content of the bottle 13 or a type of theprocessing gas, it is preferable to introduce the microwave in such amanner 100 W to 1000 W is provided per bottle, for example.

Although a processing time of, e.g., 1 second or more is required perbottle in order to assure the stability of the plasma processing, ashorter time is preferable in terms of a cost.

It is to be noted that the microwave to be introduced is not restrictedin particular as long as it acts on the processing gas to generate glowdischarge like the first embodiment, but it is preferable to use themicrowave having a frequency of 2.45 GHz, 5.8 GHz or 22.125 GHz which isallowed for an industrial use.

After performing the plasma processing, supply of the processing gas andintroduction of the microwave are stopped, and air is graduallyintroduced through the exhaust pipe 3 so that the inside and outside ofthe bottle are returned to an ordinary pressure. Thereafter, the hood 12is removed, the bottle fixing means 14 is moved up, and the bottlesubjected to the plasma processing is removed to the outside of theplasma processing chamber 1.

[Another Control Example Concerning Microwave Plasma Processing Method]

Another control example in the microwave plasma processing deviceaccording to this embodiment including the ignition gap 146 will now bedescribed.

In the foregoing embodiment, the ignition gap 146 is previously providedbefore introducing the microwave into the processing chamber 1, andignition of the plasma is carried out with introduction of the microwavebeing determined as a starting point (a trigger). However, the presentinvention is not restricted thereto, an ignition timing of the plasmacan be controlled by controlling the ignition gap 146 as will bedescribed later, for example.

FIG. 8 is a view illustrating another control example concerning thecontrol of the microwave output of the ignition gap in the plasmaprocessing method according to this embodiment.

In this embodiment, the step until introduction of the plasma is thesame as the above-described processing step except that the ignition gap146 is not provided.

In this processing step, since the ignition gap 146 is not providedbefore starting introduction of the microwave into the plasma processingchamber 1, a lower limit output (Mw4) with which plasma emission ispossible in the plasma processing chamber 1 is high.

In this state, introduction of the microwave is started (t1). An output(Mw1) of the microwave which is introduced at a low output is a valuewhich is higher than an emission lower limit output (Mw3) in case ofproviding the ignition gap 146 and lower than an emission lower limitoutput (Mw4) in case of providing no ignition gap 146. As a result, evenwhen the microwave is introduced into the plasma processing chamber 1,plasma ignition is not performed, and the processing of the bottle 13using the plasma is not started.

According to this method, a time of the entire step can be reduced by,e.g., overlapping a time required for start of the microwave oscillator4 and a time required for sufficient gas replacement.

Then, after an output of the microwave reaches a set value (Mw1) and isstabilized, the ignition gap 146 is provided by moving down the sealingmember fixing frame 145 in the longitudinal direction.

Consequently, as shown in FIG. 8, the plasma emission lower limit outputin the plasma processing chamber 1 lowers from Mw4 to Mw3, and theplasma can be ignited even with the microwave output (Mw1) in alow-output state. Therefore, with a time point at which the ignition gap146 is provided being determined as a starting point (t2), plasmaignition can be performed.

After entering the state in which the ignition gap 146 is provided,plasma emission is started after an induction time (t3).

Since a plasma ignition operation is carried out in a state where themicrowave output is stabilized in this method, the induction time can beset to a fixed and shortest time. Therefore, in case of performingprocessing of, e.g., a plurality of bottles, a plasma processing time ofeach bottle can be set further constant, the qualities of the respectivebottles can be further homogenized.

After starting plasma emission, the processing is carried out like theprocessing steps mentioned above.

As described above, according to the microwave plasma processing deviceof this embodiment, the time from introduction of the microwave into theplasma processing chamber to plasma emission can be shortened byproviding and setting the plasma ignition gap between the microwavesealing member and the end surface of the bottle holding portion, and aplasma ignition start timing can be controlled by controllingpresence/absence of the plasma ignition gap.

Third Embodiment

A plasma processing gas supply member according to a third embodiment ofthe present invention will now be described with reference to FIGS. 9 to11.

This embodiment is an embodiment in which a gas supply pipe comprising aporous pipe having an aperture distribution in a lengthwise direction isused as a plasma processing gas supply member according to the presentinvention.

[Plasma Processing Gas Supply Member]

FIG. 9 shows a preferred typical example of a plasma processing gassupply member according to the third embodiment of the presentinvention. A gas supply member 20 shown in this drawing is, e.g., a gassupply member (see the processing gas supply member 15 depicted in FIGS.2 and 3) which is used in such a plasma processing device as describedin conjunction with the first and second embodiment, and comprises ahollow cylindrical supply shaft 21 and a hollow porous tubular portion22 which is joined to an end of this cylindrical holding shaft 21 by,e.g., welding and has a closed end portion. Furthermore, a predeterminedgas is supplied into the porous tubular portion 22 through a hollowportion of the cylindrical support shaft 21, and the gas is sprayedoutwardly from a porous wall portion.

The porous tubular portion 22 has a reference area A having apredetermined aperture and a gas blowing quantity adjustment area Bhaving an aperture smaller than that of the reference area A. As shownin FIG. 9, the gas blowing quantity adjustment area B is formed at anend portion of the gas supply member, and the reference area A is formedin an area other than this end portion.

Moreover, by placing the gas blowing quantity adjustment area B of thisend portion at a position having a high electric field intensity inchemical plasma processing, a thickness of a plasma processing filmformed at this position is adjusted, thereby forming the plasmaprocessing film having an even thickness as a whole.

Here, taking formation of a plasma processing film on an inner surfaceof a plastic bottle as an example, it is preferable to set an aperturein the reference area A in such a manner that a nominal filteringaccuracy falls in a range of 10 to 100 μm, especially 10 to 40 μm. Thatis, if the aperture in the reference area A is large more thannecessary, a gas blowing quantity from the entire porous tubular portion22 is increased, and hence there is the possibility that partiallyadjusting the gas blowing quantity by the gas blowing quantityadjustment area B is difficult and, further, if the aperture is smallmore than necessary, setting the balance of the aperture with theadjustment area is difficult, and, hence a fixed thickness with respectto a film to be formed cannot be assured. It is to be noted that thenominal filtering accuracy is one of characteristic values used when aporous body is utilized as a filter, and, e.g., a nominal filteringaccuracy 100 μm means that a foreign particle having the above-describedparticle diameter can be captured when this porous body is used for thefilter.

Moreover, it is preferable for the aperture in the gas blowing quantityadjustment area B to have a size corresponding to 10 to 80% of thenominal filtering accuracy in the reference area A, e.g., the nominalfiltering accuracy of approximately 5 to 30 μm. That is, the meaning ofprovision of the gas blowing quantity adjustment area B becomes subtlewhen the aperture of this area B is close to the aperture of thereference area A, and there is the possibility of a disadvantage, e.g.,an extremely reduced thickness at a part corresponding to the adjustmentarea B when the aperture in the area B is too small as compared with theaperture of the reference area A.

Additionally, a length of the gas blowing quantity adjustment area Bvaries depending on an entire length or a diameter of the porous tubularportion B or the plasma processing device to which this gas supplymember is applied and cannot be generally specified, but generallysetting a length of 5 to 60 mm can suffice when performing the plasmaprocessing on the inner surface of, e.g., a plastic bottle.

Further, in the example shown in FIG. 9, the gas blowing quantityadjustment area B is formed at the end portion of the porous tubularportion 22, but the adjustment area B can be formed at an arbitraryposition corresponding to a part where an electric intensity isincreased in accordance with a configuration or the like of the plasmaprocessing device in place of the end portion.

Furthermore, although the aperture of the gas blowing quantityadjustment area B is set smaller than that of the reference area A inthe above example, the area B may have an aperture larger than that ofthe reference area A in some cases. That is, when a part where anelectric field intensity is considerably low exists because of aconfiguration or the like of the plasma processing device and a filmhaving a predetermined thickness is hard to be formed at this part, afilm having an even thickness as a whole can be formed by forming theadjustment area B having an aperture larger than that of the referencearea A in accordance with this part.

It is to be noted that the porous tubular portion 22 may be formed of anarbitrary porous material as long as it includes the reference area Aand the gas blowing quantity adjustment area B with predeterminedapertures in this embodiment, but it is preferable for the poroustubular portion 22 to be formed of a porous metal, e.g., bronze powerparticles or stainless steel power particles in terms of facilitation ofgeneration of plasma based on microwave glow discharge.

Moreover, in regard to the gas supply member according to thisembodiment comprising such a porous tubular portion 22, it is goodenough to mold and sinter rings having a predetermined aperture, thenjoin them by, e.g., welding to be integrated, and further join theintegrated ring to the cylindrical support shaft 21 by, e.g., welding.It is to be noted that the cylindrical support shaft 21 may be formed ofan arbitrary material such as various kinds of metals or resins, but itis preferable to use the same kind of metal as that of the poroustubular portion 22 in order to facilitate occurrence of plasma bymicrowave glow discharge like the porous tubular portion 22.

Additionally, the porous tubular portion 22 may be formed of anarbitrary porous material, but holes can be formed through a non-porousmetal pipe to provide the porous tubular portion 22, for example.

Further, if the porous tubular portion 22 is formed of a metal, since anelectric field intensity distribution is generated along a longitudinaldirection of this porous tubular portion 22 and a part having themaximum electric field intensity is generated in an area close to theend portion when performing the plasma processing, forming the gasblowing quantity adjustment area B at the end portion is most preferableas shown in FIG. 9.

Although the gas supply member according to this embodiment includingthe porous tubular portion 22 is most preferably used for formation of achemical plasma processing film on an inner surface of a container,especially a plastic bottle, it is desirable to provide a chip having agas discharge opening at the end of the porous tubular portion 22 inorder to assure a film thickness at the bottom portion thereof inparticular.

FIG. 10 shows an example of the gas supply member comprising such achip.

In this drawing, the end of the porous tubular portion 22 is opened, anda chip 23 is provided at this end. For example, gas discharge openings23 a, 23 b and 23 c communicating with the inside of the porous tubularportion 22 are formed through this chip 23, the discharge opening 23 astraightly extends along the longitudinal direction of the poroustubular portion 22 to communicate with the outside, and the dischargeopenings 23 b and 23 c obliquely extend with respect to the longitudinaldirection of the porous tubular portion 22 to communicate with theoutside.

In case of inserting the gas supply member into the bottle andperforming the plasma processing of the bottle inner surface, although athickness of a processing film is reduced at the bottom portion of thebottle, the thickness of the processing film can be increased at thebottom portion of the bottle by adopting such a configuration as shownin FIG. 10. Namely, that is because a processing film forming gas supplyquantity is increased by the gas discharge opening 23 a at the center ofthe bottle bottom portion, and the processing film forming gas supplyquantity is increased by the gas discharge openings 23 b and 23 c at arim portion of the bottle bottom portion.

Incidentally, it is good enough to form such a chip 23 by using the samemetal as that of the porous tubular portion 22. Furthermore, diameters,the number, a discharge direction or combinations of the gas dischargeopenings can be appropriately set based on a film thickness at thecontainer bottom portion or the balance with the gas blowing quantityfrom the porous tubular portion.

[Plasma Processing Device and Method]

Although he gas supply member according to this embodiment having theabove-described configuration can be applied to the microwave plasmaprocessing or high-frequency plasma processing, it is most effective toapply this member to the microwave plasma processing to form aprocessing film on the inner surface of a plastic bottle.

For example, this member can be used as, e.g., the gas supply member(the processing gas supply member 15) of the microwave plasma processingdevice according to the present invention shown in FIGS. 1 to 3. In thiscase, the same plasma processing as that described in conjunction withthe first and second embodiments is carried out under the sameprocessing conditions. The container as a processing target, theprocessing gas and other processing conditions can be the same as thoseof the first and second embodiments.

Incidentally, in case of applying the gas supply member according tothis embodiment to the microwave plasma processing device, it ispreferable to specify a distance (D) between the microwave sealingmember and the bottle fixing means, a connection position (H) of themicrowave introducing means or a plasma ignition gap (G) such as thosedescribed in the first and second embodiments to predetermined values inthe plasma processing device, but the gas supply member according tothis embodiment can be used in the plasma processing device having nosuch specification of these values.

When the plasma processing is carried out by using the gas supply memberaccording to this embodiment, a processing film having an even thicknesswith very small fluctuation band can be formed on, e.g., the innersurface of a bottle as described above, and a processing film having athickness comparable to an inner surface of a trunk portion can be alsoformed on the bottle bottom portion in case of using the gas supplymember having the chip with predetermined gas discharge openingsprovided at the end thereof.

FIG. 11 shows a relationship between a thickness of the plasmaprocessing film (a silicon oxide film) and a height from the bottlebottom, the plasma processing film being formed by microwave glowdischarge caused by inserting the gas supply member according to thisembodiment into the plastic bottle and supplying a source gas into thebottle. It is to be noted that an insertion position of the gas supplymember is indicated by “X” or “Y” in FIG. 11, and the gas supply memberis illustrated outside the bottle for the convenience's sake, but thegas supply member is actually arranged in the bottle.

In the illustrated example, a bottle which has an internal volume of 500ml and is formed of polyethylene terephthalate is inserted into theplasma processing chamber (the chamber), 3 sccm of an organic siloxanecompound gas and 30 sccm of an oxygen gas are supplied as the processinggas while maintaining 20 Pa in the bottle, and a microwave of 500 W isapplied for six seconds while maintaining a part inside the plasmaprocessing chamber and outside the bottle at 3000 Pa, thereby performingthe chemical plasma processing.

Moreover, when a porous pipe having an aperture with a nominal filteringaccuracy of 120 μm is inserted to a position indicated by Y as the gassupply member to perform the plasma processing, a thickness of a filmformed on the inner surface of the bottle is approximately 25 nm at acentral part of the bottle trunk portion and approximately 17 μm at abottle shoulder portion as indicated by a curve C, the thickness isreduced from the central part of the bottle trunk portion to the bottomportion, a thickness is as small as approximately 3 nm on the innersurface of the bottom portion, and a fluctuation band of the filmthickness is as large as approximately 22 nm.

Additionally, when an aperture (the nominal filtering accuracy) of thestainless pipe is 10 μm, a chip having a gas discharge opening of φ0.5mm is provided at an axial center part of the end of the pipe in orderto assure a film thickness at the bottle bottom portion, a length of thepipe is set to be an integral multiple of a half wavelength of themicrowave to set the insertion position at a position indicated by X,and the pipe is deeply inserted to a position close to the bottomportion of the bottle to perform the plasma processing, a film thicknesson the bottle inner surface is increased to approximately 12 nm at thebottle bottom portion as indicated by a curve B, and a fluctuation bandof the film thickness is greatly reduced to approximately 7 nm, but afluctuation band is not sufficiently reduced from the trunk portion tothe shoulder portion of the bottle.

Thus, in accordance with this embodiment, when an end portion area (a 30mm area from the end) of the stainless pipe is set to have a smalleraperture whose nominal filtering accuracy is 10 μm and the remainingarea is determined as an area having the nominal filtering accuracy of20 μm to perform the same plasma processing, approximately 10 nm of thefilm thickness is assured at the bottle bottom portion as indicated by acurve A, and the fluctuation band of the film thickness can be greatlyreduced to approximately 3 nm.

That is, in case of performing the chemical plasma processing by usingthe metal gas supply member according to this embodiment, an electricfield intensity becomes high and low along the gas longitudinaldirection, and the electric field intensity becomes maximum in thevicinity of the end portion of the gas supply member. As a result,formation of the plasma is facilitated at the maximum level at a partwhere the electric field intensity becomes highest, thereby maximizing athickness of the plasma processing film.

As described above, in this embodiment, the aperture of the porous pipeused as the chemical plasma processing gas supply member is distributedalong the longitudinal direction, and the gas blowing quantityadjustment area with a smaller aperture is formed in accordance withsuch a part having the large electric field intensity as mentioned abovefor example, thereby reducing the maximum thickness and forming a plasmaprocessing film having an even thickness as a whole with a smallfluctuation band of the film thickness.

As described above, according to the plasma processing gas supply memberof this embodiment, the porous pipe having an aperture distribution inthe lengthwise direction is used as the gas supply member which suppliesthe processing gas into the plasma processing chamber of the plasmaprocessing device, especially the porous pipe having the gas blowingquantity adjustment area in which an aperture is relatively small beingformed at the end portion thereof is used, thereby forming a plasmaprocessing film with an even thickness on an inner surface of acontainer as a processing target and an inner surface of a plasticbottle in particular.

Fourth Embodiment

A plasma processing gas supply member according to a fourth embodimentof the present invention will now be described with reference to FIGS.12 to 16.

This embodiment is an embodiment in which a gas supply member which issectioned into a metal electric field intensity distribution stabilizingarea and a non-metal end gas induction area is used as the plasmaprocessing gas supply member according to the present invention.

[Plasma Processing Gas Supply Member]

FIG. 12 shows preferred typical examples of a plasma processing gassupply member according to the fourth embodiment of the presentinvention. A gas supply member 30 shown in this drawing is the same asthe gas supply member 20 according to the third embodiment, e.g., a gassupply member (see the processing gas supply member 15 shown in FIGS. 2and 3) used in the plasma processing device described in the first andsecond embodiments, and comprises a hollow cylindrical support shaft 31and a gas supply pipe 32 joined to an end of this cylindrical supportshaft 31 by, e.g., welding.

Specifically, the gas supply member 30 has a configuration in which apredetermined reactive gas (a plasma processing gas) is supplied intothe gas supply pipe 32 through a hollow portion of the support shaft 31and the gas is sprayed outwardly from a pipe wall portion and the endportion, and the reactive gas is supplied into a plasma processing area(the inside of a container) when this gas supply pipe 32 is insertedinto a container (see the bottle 13 shown in FIGS. 2 and 3) held in,e.g., the plasma processing device depicted in FIGS. 1 to 3.

Furthermore, in this embodiment, the gas supply pipe 32 is configured tobe sectioned into an electric field intensity distribution stabilizingarea A and an end gas induction area B positioned on the end portionside of the area A.

In the example depicted in FIG. 12, the electric field intensitydistribution stabilizing area A of the gas supply pipe 32 is formed of ametal porous pipe 32 a, and has an effect of spraying the gas toward theperiphery through a pipe wall thereof, supplying the gas into thecontainer held in the plasma processing device, forming an excellentresonating system in the plasma processing area (the inside of thecontainer), increasing an electric field intensity in a plasmaprocessing area (the inside of the container) and stabilizing anelectric field intensity distribution along an axial direction of thecontainer to be processed. Therefore, in this area A, the gas supplypipe 32 must be a porous pipe and formed of a metal in order to supplythe gas toward the periphery. When the pipe wall is formed of, e.g., anon-metal material, the above-described electric field intensityadjustment function cannot be demonstrated.

Moreover, in order to demonstrate the above-described electric fieldintensity adjustment function, the metal porous pipe 32 a constitutingthis electric field intensity distribution adjustment area A iselectrically connected with a shield wall constituting the plasmaprocessing chamber, and an axial length of this pipe is set to have adefinite relationship with respect to a half wavelength (λ/2) of themicrowave used for the plasma processing. Therefore, although the axiallength of the metal porous pipe 32 a (the axial length of the electricfield intensity distribution stabilizing area A) cannot be generallyspecified, this length is generally approximately 170 to 190 mm when aplastic bottle having a capacity of 500 ml is taken as an example.

In this embodiment, the metal porous pipe 32 a may be formed of anarbitrary metal as long as the above-described electricalcharacteristics are assured, it is preferable for this pipe to be formedof bronze power particles or stainless steel power particles in terms ofthe moldability or the like.

Additionally, it is preferable for the metal porous pipe 32 a to have anaperture with which the nominal filtering accuracy becomes 300 μm orbelow and falls within a range of 2 to 150 μm in particular in order toevenly supply the gas through the pipe wall.

Further, the metal porous pipe 32 a may have a fixed aperture as awhole, the aperture may be distributed along the axial direction of thispipe. That is, when performing the plasma processing based on themicrowave, the electric field intensity is distributed along the axialdirection of the gas supply member (or the container), and the maximumelectric field intensity part and the minimum electric field intensitypart are alternately repeated with, e.g., a half wavelength (λ/2) of themicrowave being determined as approximately one cycle, but the endportion of the metal porous pipe 32 a becomes a singular point ofelectric field concentration and tends to have a large thickness.Therefore, in such a case, reducing the aperture at this part canfurther homogenize the thickness of the vapor deposition film to beformed along the axial direction, for example.

Such a metal porous pipe 32 a can be formed by, e.g., forming andsintering rings having a predetermined aperture, then joining andintegrating these rings by using welding or a screw configuration, andthe obtained pipe can be also joined to the cylindrical support shaft 31by welding, a screw configuration or the like.

In the example shown in FIG. 12, although the cylindrical support shaft31 may be formed of various kinds of metal materials as long ascommunication with the shield wall constituting the plasma processingchamber can be obtained, it is preferable for the cylindrical supportshaft 31 to be formed of the same metal as the porous metal constitutingthe metal porous pipe 32 a.

Furthermore, the end gas induction area B is constituted of a non-metalpipe 32 b consisting of an electrically insulating non-metal material.That is, this area B is formed in order to spray the gas toward thebottom portion of the container without adversely affecting the electricfield intensity distribution stabilized by the area A. Therefore, a pipewall of this non-metal pipe 32 b may have an aperture like that of themetal porous pipe 32 a, but the aperture may be not formed through thepipe wall as long as a through hole which communicates with the insideof the metal porous pipe 32 a from the end thereof and pierces the endportion of the non-metal pipe 32 b is formed.

For example, the conformation shown in FIG. 12(a) is an example in whichno aperture is formed through the pipe wall of the non-metal pipe 32 b,and a through opening 32 c communicating with the inside of the metalporous pipe 32 a pierces the end of the non-metal pipe 32 b in thiscase. On the other hand, the conformation shown in FIG. 12(b) is anexample in which the aperture is formed through the pipe wall of thenon-metal pipe 32 b, and the end of the through opening 32 c is closedby the pipe wall, but the aperture is formed through the pipe wall andthere is no problem in spraying the reactive gas in this case.

There are various kinds of resins or ceramics as the non-metal materialforming the non-metal pipe 32 b, a fluorocarbon resin or ceramics suchas alumina is preferable in terms of the heat resistance, the strength,a cost and others. This non-metal pipe 32 b can be molded by a knownmethod such as an injection molding method, an extrusion method, acompression molding method, a baking method, a cutting method or thelike in accordance with a type of a material constituting this pipe, andthe non-metal pipe 32 b is joined to the end of the metal porous pipe 2a by using a screw configuration or an appropriate adhesive as required.

Since an axial length of the non-metal pipe 32 b is determined inaccordance with an axial length of the metal porous pipe 32 a or anaxial length of a container to which a CVD film should be formed andcannot be generally specified, and hence it usually falls within a rangewhich is less than a half wavelength (λ/2) of the microwave. Namely,that is because a gap between the end of the metal porous pipe 32 a andthe container bottom portion is usually less than λ/2.

Furthermore, it is preferable that the axial length of this non-metalpipe 32 b is set in such a manner that a gap between the this pipe andthe container bottom portion becomes approximately 1 to 40 mm. That is,a thickness of the CVD film formed on the container bottom portion tendsto be insufficient when this gap exceeds the above-described range, anda thickness of the CVD film formed along the periphery tends to beinsufficient as compared with the central part of the bottom portionwhen the gap is smaller than the range.

It is to be noted that the gas supply member according to thisembodiment is not restricted to the example shown in FIG. 12, and it ispossible to adopt, e.g., a configuration depicted in FIG. 13. That is,although the metal part forming the electric field intensitydistribution stabilizing area A is formed of the pipe wall in the gassupply member depicted in FIG. 12, the metal part is formed of a membercompletely different from the pipe wall in the example shown in FIG. 13,and this point is a significant difference.

As shown in FIGS. 13(a) and (b), in this gas supply member, the entiregas supply pipe 32 joined to the end of the hollow cylindrical supportshaft 31 is formed of the non-metal porous pipe, and a metal rod 33(having the same electric field intensity distribution adjustmentfunction as that of the metal porous pipe 32 a in the gas supply pipedepicted in FIG. 12) which specifies the electric field intensitydistribution stabilizing area A is provided in this gas supply pipe 32.

The metal rod 33 extends in the non-metal gas supply pipe 32 from a rootportion thereof, and an area in which this metal rod 33 is providedserves as the electric field intensity distribution stabilizing area A,and an area beyond the end of this metal rod 33 (an area where the metalrod 33 is not provided) functions as the end gas induction area B.

In this example shown in FIG. 13, the entire non-metal gas supply pipe32 is formed of the same non-metal material (e.g., a resin such as afluorocarbon resin or ceramics such as alumina) as that of the non-metalpipe 32 b depicted in FIG. 12, and the non-metal gas supply pipe 32 hasthe same aperture as that of the metal porous pipe 32 a in the electricfield intensity distribution stabilizing area A. That is, the aperturemay not be formed in the end gas induction area B, and the axial lengthof the electric field intensity distribution stabilizing area A or theend gas induction area B can be set like the gas supply pipe depicted inFIG. 12.

Furthermore, since the metal rod 33 forms the electric field intensitydistribution stabilizing area A, it must be electrically connected withthe shield wall constituting the plasma processing chamber in the plasmaprocessing device (see FIGS. 1 to 3). Therefore, in case of FIG. 13, thehollow-cylindrical support shaft 31 is formed of a metal, andcommunication between the metal rod 33 and the shield wall constitutingthe plasma processing chamber must be achieved through this metalcylindrical support shaft 31. Therefore, a rod support portion 31 a isprovided at the end portion of the metal cylindrical support shaft 31 insuch a manner that communication between the inner path of the supportshaft 31 and the inside of the non-metal gas supply pipe 32 is notjeopardized, and the metal rod 33 is supported by this support portion31 a (see FIG. 13(b)).

It is to be noted that this metal rod 33 may be formed of an arbitrarymetal material, it is preferable for the metal rod 33 to be formed ofthe same material as that of the metal porous pipe 32 b in terms of theoxidation resistance.

[Plasma Processing Device and Method]

The gas supply member according to this embodiment having theabove-described configuration is used as, e.g., the gas supply member ofthe microwave plasma processing device according to the presentinvention shown in FIGS. 1 to 3 like the gas supply member described inconjunction with the third embodiment. It is preferable to useprocessing steps or processing conditions which are the same as thosedescribed in the first and second embodiments.

It is to be noted that the gas supply member according to thisembodiment can be also used in the plasma processing device according tothe second embodiment in which the distance (D) between the microwavesealing member and the bottle fixing means, the connection position (H)of the microwave introducing means or the plasma ignition gap (G) is notspecified like the third embodiment.

Here, a container subjected to the plasma processing by the gas supplymember according to this embodiment may be a container 100 in which aplanar cross-sectional shape of a trunk portion thereof is a circularaxisymmetrical shape as shown in FIG. (14 a), or may be a container 200in which a planar cross-sectional shape of the same is anon-axisymmetrical shape like a rectangular shape shown in FIG. 14(b)and, in any case, an even CVD film having small irregularities inthickness along a circumferential direction can be formed on an innersurface of the trunk portion even in the container 200 having such anon-axisymmetrical shape as shown in FIG. 14(b) in particular byinserting the gas supply member 30 on an axial center of the containerto form an excellent resonating system.

Moreover, in this embodiment, in order to form the excellent resonatingsystem along the axial direction by the gas supply member 30 whenperforming the plasma processing based on supply of the microwave,increase the electric field intensity and stabilize the electric fieldintensity distribution along the axial direction, it is preferable toset a length of the electric field intensity distribution stabilizingarea A, i.e., a length of the metal porous pipe 2 a in such a mannerthat a length (see L shown in FIGS. 2 and 3) from the micro sealingmember (see FIGS. 2 and 3) of the plasma processing chamber to aboundary portion between the electric field intensity distributionstabilizing area A and the end gas induction area B (corresponding tothe end of the metal porous pipe 2 a) becomes (nλ/2)±10 mm (n is aninteger not less than 1) with respect to the wavelength λ of themicrowave.

Additionally, in order to form a CVD film having a sufficient thicknesson the bottom portion of the container and form a CVD film having aneven thickness even in case of a container having a non-axisymmetricalshape such as shown in FIG. 14(b), it is preferable to set the axiallength of the end gas induction area B in such a manner that a gapbetween the end of the gas supply pipe 32 and the container bottomportion becomes 1 to 40 mm.

By performing the plasma processing using the gas supply member 30according to this embodiment in this manner, a processing film having avery small fluctuation band of a thickness and having an even thicknesscan be formed on an inner surface of the bottle.

As described above, according to the plasma processing gas supply memberof this embodiment, by constituting the gas supply pipe on the end sideof the gas supply member to be sectionalized in two areas, i.e., themetal electric field intensity distribution stabilizing area and thenon-metal end gas induction area, the plasma processing area can beformed as the excellent resonating system, the electric field intensityof the plasma processing area can be increased, and the electric fieldintensity distribution can be also stabilized along the axial directionof the container to be processed. As a result, the plasma processing gassupplied from the gas supply member can be efficiently and evenly turnedto the plasma, thereby forming a uniform thin film to a processingtarget.

Embodiment

Excellent advantages of the plasma processing gas supply memberaccording to the fourth embodiment of the present invention will now bedescribed hereinafter based on concrete experimental examples.Incidentally, it is needless to say that the gas supply member accordingto the present invention is not restricted to the following examples.

Common Conditions

Common conditions are determined as follows and experiments ofrespective examples were conducted.

A biaxial drawing prismatic bottle formed of polyethylene terephthalatewhose cross-cross sectional shape has the oblateness of 1:1.3 was usedas a substrate which is a processing target.

An organic silicon compound gas and oxygen were used as a processingsource gas, and gas flow quantities were set to 2 sccm in case of theorganic silicon compound gas and 20 sccm in case of oxygen.

Degrees of vacuum were determined as 20 Pa inside the bottle and 7000 Paoutside the bottle.

A microwave was oscillated by using a microwave power supply of 2.45GHz, and processing was performed for 10 seconds at an output of 500 Wafter plasma ignition.

A stainless pipe material (whose length is 35 mm: included in a lengthof a part A shown in Table 3) was used as the support portion of the gassupply member.

Evaluation of Film Thickness Distribution

By measuring a quantity of Si in a film at each measurement position cutout from a vapor deposition sample by using a fluorescent X-ray devicemanufactured by Rigaku Corporation and converting a measured result froman analytical curve into a film thickness, a film thickness distributionin a height direction (FIG. 15: a value at each height is an averagevalue of circumferential four directions) and a difference (FIG. 16: aheight position of 60 mm) between an average film thickness in 0 and180° directions and an average film thickness in 90 and 270° directionswere obtained.

EXPERIMENTAL EXAMPLES

In regard to a configuration or a length of the gas supply member,experiments were conducted based on combinations of conditions shown inTable 3. It is to be noted that a gas supply member which is entirelyformed of a metal porous pipe was used as Comparative Example 1. TABLE 3Film thickness measurement result Material Length mm HeightCircumferential Conditions Configuration Part A Part B Part A Part Bdirection direction Embodiment 1 FIG. 1(a) SUS porous Fluorocarbon resin180* 40 ⊚ ⊚ Embodiment 2 material pipe with φ1 hole 15 ◯ ⊚ see FIG. 15Embodiment 3 SUS rod + ceramic Ceramic porous pipe 40 ◯ ⊚ porous pipeComp. SUS porous — 0 X X Example 1 pipe(part A: the electric field intensity distribution stabilizing area,part B: the end gas induction area)(mark *: when the part A = 180 mm, a distance to the bottle bottom = 50mm)[Result-1]

It was confirmed from Table 3 and FIG. 15 that a film thickness isincreased on the bottle bottom portion since the source gas reached thebottle bottom portion, and the rather large film thickness which isobserved in Comparative Example 1 is improved in the vicinity of aposition which is 40 to 100 mm of the trunk portion so that a filmthickness difference (the maximum value—the minimum value) in the heightdirection becomes small under all experimental conditions (Embodiments 1to 3) satisfying claims of the present invention. Incidentally, it canbe considered that the large film thickness at the trunk portionobserved in Comparative Example 1 is improved by provision of the endgas induction area because the flow quantity balance of the bottomportion and the trunk portion is enhanced when the source gas having afixed supply quantity is partially led to the bottom portion.

[Result-2]

It was confirmed from Table 3 and FIG. 16 that a film thicknessdifference between the long side portion (0 and 180° directions) and theshort side direction (90 and 270° directions) is large under theconditions of Comparative Example 1 in which the end gas induction areais not provided, whereas this is improved under the experimentalconditions (Embodiments 1 to 3) satisfying claims of the presentinvention.

INDUSTRIAL APPLICABILITY

As described above, the microwave plasma processing device and theplasma processing gas supply member according to the present inventionare useful as a plasma processing device and a gas supply pipe which canstably and efficiently generate plasma, and they are suitable formicrowave plasma processing in particular.

1. A microwave plasma processing device having: fixing means for fixinga substrate as a processing target on a central axis in a plasmaprocessing chamber; exhausting means for depressurizing the inside andoutside of the substrate; a metal processing gas supply member which ispresent in the substrate and forms a reentrant cylindrical resonatingsystem along with the plasma processing chamber; and microwaveintroducing means for introducing a microwave into the plasma processingchamber to perform processing, wherein a microwave sealing member isprovided at a substrate-holding portion of the fixing means, a distance(D) between the microwave sealing member and a surface of the fixingmeans positioned in the plasma processing chamber is 0 to 55 mm, and adistance (L) between the microwave sealing member and an end portion ofthe processing gas supply member satisfies the following relationalexpressions: A. in case of 0≦D<20L=(nλ/2+λ/8)−3+α B. in case of 20≦D≦35L=(nλ/2+λ/8)−(−0.060 D²+4.2 D−57)+α C. in case of 35<D≦55L=(nλ/2+λ/8)−(−0.030 D²+2.1 D−21)+α [where n is an integer, λ is awavelength of the microwave, and α is a fluctuation band considering aninfluence and the like of the substrate on an electric field and is ±10mm].
 2. A microwave plasma processing device having: fixing means forfixing a substrate as a processing target on a central axis in a plasmaprocessing chamber; exhausting means for depressurizing the inside andoutside of the substrate; a metal processing gas supply member which ispresent in the substrate and forms a reentrant cylindrical resonatingsystem along with the plasma processing chamber; and microwaveintroducing means for introducing a microwave into the plasma processingchamber to perform processing, wherein a microwave sealing member isprovided at a substrate-holding portion of the fixing means, and aconnection position of the microwave introducing means is a positionwhere an electric field is weak in an electric field intensitydistribution formed in the plasma processing chamber.
 3. The microwaveplasma processing device according to claim 2, wherein a distance (D)between the microwave sealing member and a surface of the fixing meanspositioned in the plasma processing chamber is 0 to 55 mm, and adistance (H) between the microwave sealing member and the connectionposition of the microwave introducing means satisfies a relationship ofthe following expression:H=L−(n ₂λ/2+λ/8−3)+β(mm) where n₂ is an integer satisfying n₂≦n₁−1, λ isa wavelength of the microwave, β is a fluctuation band caused due to adimension or the like of the substrate and is +10 mm, and L is adistance between the microwave sealing member and the end portion of theprocessing gas supply member and satisfies the following relationships:A. in case of 0≦D<20L=(n ₁λ/2+λ/8)−3+α B. in case of 20≦D≦35L=(n ₁λ/2+λ/8)−(−0.060 D²+4.2 D−57)+α C. in case of 35<D≦55L=(n ₁λ/2+λ/8)−(−0.030 D²+2.1 D−21)+α [where n₁ is an integer which isnot smaller than 1, λ is a wavelength of the microwave, and α is afluctuation band in consideration of an influence and the like of thesubstrate on an electric field and is ±10 mm]].
 4. A microwave plasmaprocessing device having: fixing means for fixing a substrate as aprocessing target on a central axis in a plasma processing chamber;exhausting means for depressurizing the inside and outside of thesubstrate; a metal processing gas supply member which is present in thesubstrate and forms a reentrant cylindrical resonating system along withthe plasma processing chamber; and microwave introducing means forintroducing a microwave into the plasma processing chamber to performprocessing, wherein a plasma ignition gap is formed on an end surfaceside of the substrate-holding portion of the fixing means and themicrowave sealing member is provided in the formed gap.
 5. The microwaveplasma processing device according to claim 4, wherein driving means forrelatively moving the microwave sealing member and the substrate-holdingportion to the plasma processing device forming the microwave reentrantcylindrical resonating system, and the microwave sealing member and thesubstrate-holding portion are relatively moved by this driving means toadjust the plasma ignition gap between the microwave sealing member andthe end surface of the substrate-holding portion.
 6. A chemical plasmaprocessing gas supply member comprising a porous pipe having an aperturedistribution in a lengthwise direction.
 7. The chemical plasmaprocessing gas supply member according to claim 6, wherein, in theporous pipe, a reference area having a fixed aperture and a blowingquantity adjustment area having an aperture smaller than that of thereference area are formed in the lengthwise direction.
 8. The chemicalplasma processing gas supply member according to claim 7, wherein theblowing quantity adjustment area is formed at an end portion.
 9. Aplasma processing gas supply member comprising a gas supply pipe whichis inserted into a container held in a plasma processing chamber intowhich a microwave is introduced and supplies a reactive gas which issued to form a CVD film on an inner surface of the container, whereinthe gas supply pipe is sectionalized into two areas, i.e., an electricfield intensity distribution stabilizing area and an end gas inductionarea which is positioned on an end side with respect to the electricfield intensity distribution stabilizing area, at least a metal portionwhich communicates with a shield wall constituting the plasma processingchamber and extends from a root portion to a boundary between theelectric field intensity distribution stabilizing area and the end gasinduction area in an axial direction is formed in the electric fieldintensity distribution stabilizing area, and the end gas induction areais formed of a non-metal material.
 10. The plasma processing gas supplymember according to claim 9, wherein the gas supply pipe comprises aporous metal pipe and a non-metal tubular end portion joined to an endof the porous metal pipe, the porous metal pipe forms the electric fieldintensity distribution stabilizing area, and the non-metal tubular endportion forms the end gas induction area.
 11. The plasma processing gassupply member according to claim 9, wherein the entire gas supply pipeis a non-metal porous pipe, a metal rod communicating with a shield wallconstituting the plasma processing chamber and extending from a rootportion in an axial direction extends inside the non-metal porous pipe,and the gas supply pipe is sectionalized into two areas, i.e., theelectric field intensity distribution stabilizing area and the end gasinduction area by this metal rod.